Supervisory alarm system.



J. G. Nom-3N. SUPERVISORY ALARM SYSTEM. APPLICATION FILED AUG.*1.'1912. 1,8%,703 Patntea 1560.30, 1913.

2 SHEETS-SHEET 1.

J. G. NOLEN.

SUPERVISORY ALARM SYSTEM. v APPLIQATIONPILED AUG.1,1912.

311m niet,

' toscana To aM whom imag concern.'

-nnrrnn STATES. ormonl JAMES G. NOLEN, 0F NEW YORK, N. Y., nASSIGrNOR TO FIRE PROTECTION DEVELOPMENT.

company, o F NEW Yoan, N. Y., A conrona'rron' or-,Manm

surnnvsomr. ALARM SYSTEM.

Be itknown that I, JAMES G..'NoLE N, -a

citizen of the United States of America, and.'

a resident of NeW`York ;in the county of New York and State`ofNevJ York, have 'invented certain new and useful'mprovements 1n Supervlsory Alarm Systems, of'

which thei following is a specification.

My invention relates t0 improvements 1n supervisory alarm systems .such as areemploycd forl indicating sudden 'and excessive rise 4in temperatures, and 'relates particularly 'to Aelectr'o-pneumatie systems, of the class 'referred to. Such systems comprise piping of small bore, laid through the spa-ceto be protected or superv1sed,and connectedto fluid-pressure-actuated alarminitiating devices, which latter devices are arranged to i be actuated by expansion of air inthe piping, caused by sudden rise of temperature; v

which pressure-actuated alarminitiating devices may. themselves indicate -the alarm, or maybe'electric contact devices adapted when actuated to transmit an alarm through an electric circuit, or' to set in operation other' transx nit't'ing means; or these fluidpressure-actuated alarm-initiating devices jmayopcrate to eect. indication of abnormal conditions, or to eifect the transmission of a signal, in various other ways. In such systems, since the alarm initiating device should not be operated by slow rise of temperature, such as may be occasioned by -natural causes, and may extend through a wide range,-it is customary to provide an esc'ape vent'through which air will escape slowly, but. with' suiiicient rapidity ,to prevent the signal-initiating device being actuated by slow rise of temperature, but which will not permitescape of air at suchrate as to prevent actuation ot the signalinitiating device when --the temperature rises rapidly. tact device has commonly been employed for each length of piping, or detector tubing,

as it is commonly called; such diaphragm' being located at, one end of the' length of detector tubing, the other end of such tubing being closed; or, the detector tubing has been arranged in the formA of a loop, both ends of which are connected to the dia'- phragln contact device, las in the patent to J. E. Shepherd, No. 884,047, dated April 7 1908, and in` mvapplicationSr.- No. 509,102, filed ugust ".23, 19.09, though in some cases Heretc'fore one diaphragm' contwo diaphragm 'contact devices haven-been employedv located respectively at the two ends of a loop of detector tubing:

According to the' present invention, in

stead of locating the diaphragm contact devices, Aor detectors as they are commonly termed, at the end or 'ends of a length of detector tubing, I locate a pluraiity of pneu.- matic contact devices or idctectors at various points intermediate the ends of a lengthiof detector tubing, spacing suchV detectors suitable ,distances apart along such tubing, 4and group; and in such cases the detectors of each -group are commonly connected electrically to a single annunciating device common to that group, the detectors of all thegroups being connected to a connnon alarm transmitting device. ln manyv cases, with pneumatic alarm initiating devices o r detectors-so located on a'single length of tubing, itisunnet-essary toprovide the individual detectors with vents; the ends of the tubing being open, in case the tubing extends for a considerable distance beyond the extreme detectors'7 cr one or both ends' of the tubing being otherwise provided with .specmpation nfreftersratent. -PatentedBeest),i913.A alpucat'ioii aleafafug'ust 11912, serial No. 712,765.'

by preference connecting such "detectors 4electrically to the same signal transmitting restricted escape means in ease'the tubing dees not exteid a' consideraliiie distance beyond one. or both extreme detectors; but in the case. ola very long length ot tubing having a large number of detectors connected to 1t, o ne or more restrict-ed escape means may be provided at an intermediate point or points 4ofthe detector -tubing, such restricted escape meansbeing,in such case, preferabl)I -on one or'more of the detectors themselves.

' .Thesystenr:embodyingthe invention ci' this application has the. unipoltant advantage ove'r systems wherenrthe detectors are .located at the end or ends of the detector tubing, that ordinarily a plurality (rf-detectors will be operated by an)v tire, the -detector nearest Vthe point of inception of the or loorii'i which the re began.

- the detectorslare located 4at the end or ei'ids detector tubing extending throughout the :irisk. et oneend of tlie length of detector .as to the sending ofthe alarm, as several de- 4effect the sending .of an alarm. The annum.

.of detectors uponra single length of tubing,

' are connected a plurality of detectors 2. I"

p being located in 'di'terent tire being, ordinarily, first operate'd, i

then the detectors-fon opposite sides' of suchY ist detector being, operated, -and so on.. Possible failure of the first detector to'opereate makes very littlediiference, therefore,

tectors on opposite sides of the' detector nearest -the point of 'inception of fire will be operated almost immediatelythereafter. The operation ofany one ofrtliese detectors will ciator of the system will indicatethe room The system herein describedhas numerous Odiel-advantages, among which are .that an alarm is obtainedmore promptly than when only of the tubing, owing to at least one de-'- tector being closer to the point ofinception' of the lire than is ordinarilypossible when the detectors are ldcatedat the ends only 'of the tubing; :and that the -syst'emis much. more easily tested, for coniinuityo tubing, andfor operativeness of allojthe detectors.

The objects of' my invention areto'iinprove and simplify pneumatic alarm .systems sucli as referred to, to increase the reliability` and efticicneypthereof, to' render the ,same more prompt in response to tires,.aiidmore certain ofresponse, and to .facilitate testing of tlie tubing, and of the detectois."

I will noiv, proceed to describe myini-'en-Il features in claims.- Y Y lu the drawings: Figure 1 ispa ,diagrams illu'strating the arrangement of a plurality drawings, and will then point out the novel and illustrating schematically only, alarm transmitting and amiunciating devices; Fig. 2 shows a Adetail vertical section of oneform of pneumatic' diaphragm or detector, such as may be 'employed, and illustrates .one method of connection of. the detector -tubing thereto. Fig. 3-is ai'ieiv' similarto Fig. 2, illustrating a further method ofcoiinection et tliedetector tubing to'the alarm 'initiat-I ing device. Fig. 4 shows a vertical section of.

the suction 'detector or contact device 4.

Fig. 5"isa viewvillustratiiw more' or less diagrammaticallyand in "section, a heat-colli testing device which may be employed.' Fig. G'is a-vieivsimilarto Fig.' 1,. excepttliat the tubing employed is endle ss.

'Referring first to Fig. 1, numeral 1 desig nates a length of detector tubing to; which have shown these detectors arranged in three groups of three each, and it may be uii'derf stood-that'eacli.' group is Alocated in asmgle room or floor o'the risk, the different-groups .rooms or on dit'-l Fercnttloors of the risk, theone length of I have illustrated a restricted-escape means 3; andI hai-'c indicated that the other end of tlie. detector `tubing extendszan in.-

'denite dista-ncebeyond the last detector,

that distance being such-.that no other restrictedesca-pemeans is required-at that end of. the detector tubiiig,'thel extension ,of the tubingitself in this -case` constituting a restricted escape means.' I have further vin di- Y cated, beyond one of the extreme detectors, -a special suction contact device 4 employed for testing purposes; and'I have further indicated beyond the other extreme. detector a connection for a suction pump 5 to be ein ployed-for testing purposes.

6 designates the controlling magnetof an alarm transmitting device, and 7 the ala-rm ivheel or break wheel'ofsuch alarm transmitting device. I do not in this vapplication illustrate the ala'riiitransinitter and the' circuits thereof in full; the same being ilustrated infullV in a companion application ilediugust 1 1912 Sr.' No. 712,764.' For t-hevpurposeA o .the present case', 'the alarm transmitter-may be any transmitter :which will be, operated by 'the' operation of any. oneof the detectors 2. For presen. purposes, the 'transmitter may be under- -stood to be one .which is operated upon the closing ofcontact between the diapliragm andcontact screw 'of'any one of the 1 detectors 2. tion with reference to tli'e :accompanying- Numeral '10 designates an annunciator oi.

.the system, icomprising, in the instance.

shown, three drop magnets. 11, 12 and 13, with corresponding magneticallyoperated dropscr shutters 118212aA and 13a ,respectively.

,. l15 designates a battery o r generator supplying current to the circuits whereby the' severalj'detectors control tliemagnet 6 of the .alarmj transmitter. For present -pur poses, itJnay be assumed that the-said 'cir-4 cuit is lfrom battery 15v -through Wire 64e to the bases of the severalV detectors 2, in se- '-ries, and thence through h65 to the coils of niagnetf6,"a nd thence back-to battery; and it may be assumed that the detectors-2 control magnet` 6, iii-that each detector, when operated, will complete a shunt 'from wire 64, tlirou'ghfits diaphragm and contact screw, to a Wire 71, or 72 or 73, as tliercase may be,- to the corresponding annunciator magnet, 11 or'12 01213, as the case may be, back to battery, the said shunt socompleted omitting thetransmittermagnct 6.' The annunciator 'magnets' will be of much Aless resistance than the transmitter magnets and hence the completion of a shunt as transmittermagnet 6. l

Referring nov'v to Fig. 2, 11.6.A designates the casing of'one of the diaphragm contact described, has the e-ect o'fdenegizing the 125 devices or detectors, 17' designates the; dia

phi'agm thereof, 18 the contact ,screw there-l of, insulated from the case 16 by 'insulating material 19, and '2O a binding-post for the electric connection ot'- a circuit conductor to' the contact scr e\ v`18. 21 designatesabracket or other means by Which-the detector maybe connected toa Wall or cellingor other' suitable support, this-bracket being in electrical connection with the case 16; and a circuit conductor is commonly connected' to' Athis bracket :21, one of the screws by which the bracket is secured to'the wall or other supports serving as a, binding screw; the circuit conductor so connected to Athe'bracket be-- pipe nipple connected to the case 16beneaththe diaphragm 17 and a 4short length.

of tine tubing, preferably glass thermometer tubing, 24, securedA to the end of the-nipple 23 by means ot,a sleeve screw 25 screwing upon Vthe nipple .23, the glass tubing. 24-being sealed in place by means of plastic. se'aling material 26; 27 designates a cover, screwing upon sleeve screw 25, and. having at its end an opening 28 to 'the external air; suitable' foraminous material 29 being .usually pro\'ided,-bett`veen the end of the glass tube '24 and -this opening 28, to prevent dust entering tube 24, Without materiallyretarding the escape ot' air'through said tub.- ing. I have found that a short glass tubeof small diameter of bore, such as the .tube 24,

isa particularly etlicient restricted escape'- mean's.' It is not ati'ected by exposure toA air orother gases, since it is-notjoxidizable and is practically inert, chemically; itisA not affected by prolonged .exposure totemperatures approaching those at whichl combustion usually occurs; it is not affected by'.

moisture; and since the diameter of its bore (usually about five-thousandths of anlmch') 'is less than that of average dnstgains, it is not affected by dust. Furthermore, such an escape means will serve lengths ofpipe varying greatly in length. It is ordinarlly required that no' 'alarm shall basent When.-

thetemperature rises at 'aratefno more 'I rapidly than-four degrees per minute,"but

that an alarm shall be given if the ternA erature rises at a greater rate. I have ound that a glass tube of the -bore referred to will serve detector tubing of about or less than in. internal diameter, varying'in' length',

from titty to nine hundred feet. For greater variations in length of detector tubing the length of the glass tube 24 may be varied.

The restricted escape means 3 sl'1o\vn. 1n Fig. `1 as connected tothe end ot: the d etector tubing' 1, may be'precisely similar -1n 22 shown in Fig. 2. Y

The detector tubingmay construction to the-restricted escape devicebe connected to the diaphragm contact device 2 in various ways. In Fig. 2 I sho-f thedetector ltubing connected to a Contact device 2'by. means ofl a T-connection 78; in Fig.' 3 I show the diaphragm 'chamber connected directly vto the detector-tubing 1. For A'testing'the contin'uity of the tubing it is convenient to'pro- .vide beyond one of'the extremedet'ectors 2, a Asuction lcoiitattlJ--device 4, and to; provide, beyond the otherextreme detector 2, a' con- 'nection for a suction pump 5. The. suction contact device 4, shown in section in Fig.`4, is in general construction thejsamevasthe detectors 2,-eXcept that the tubi-ng, 1 is con- 'ne'cted to the upperside ofthe diaphragm chamber, instead `of to the-.lower side thereof. For'the convei'iientv .connection of 'the -suction pump 5, "I commonly provide a three Way valve" 79. having gravitating handle 8th -so arranged that'normally .the 4branch p1pe81 leadingto thesuction pump is shut ofi' from the tubing 1, vsaid' tt'lbing 1 .being o'pen to the en d; while l.when the vhandle ofsaid valve'islraisedthe detector tub4-V ing 1 is connectedto'the suction 'pump and' connection to the open end of the 'tubing is.

l'shut off. If the ,tubing be intact, two or -three strokes of the suction pump will create suction enough in the-tubingfto operatethe suction contact device 4 at-theopposite end of the system theoperation of this suctionA contact device being indicated by the ringling of a. bell 82,' which bell may-be in any convenient'loeation'.

Ordinarily, the suction. pump l5 will not bel a permanent lpart of the system,lbut will be'connected thereto, `when the system is to betested, by means of a pipe union connectio-n 83,' or other convenient coupling.

Ifga pressure pump be substituted for the suction pump, the operation of the :various detectors maybe proved; in most cases, in-- steadA of employing-a pressure pump for 2proving the operativeness of the detectors 2, a testing-device,such as is shownl in-Fig. 5, and vcom]'arising a coil ,oftubing' 84 similar 'to thev detector tubing, Wound about an el'ec- Acurrent ispassed through the heater, is

communicated to the tubing'1',lwhen, fthe handle of thelva'lve 19 is raised.

The fact that -thetubing 1 is open atthe Y end, beyond 'the suction contact device 4:, does'not prevent the'test-ing of the system' by suction; 4for'ii the tubing extend for a number of feet-(say fifteen .tor moreifeet) beyond such suction Acontact device, the resistance' offered by such 'length of tubing bevond the contact device 4,l to thetlow of air, .is sufficient to restrict the inflow ooair and 'to cause the suction device 4 to operate when the suction pump is operated. In- 1 'stead of extending thetubing l1 y anumber of feet beyond the end of the suction contact device 4, a restricted escape device, such as QSE-,may be provided; the resistance offered by this device 22 to theinloW-'of air being sutiicient 'to restrict the inflow of air and to causeY the suction Contact ldevice to operate when the suction pumpis operated.

^ or at intermediate points, or at both the ends.

Since in this system the -tubing4is pro-4 vided 'with restricted escape means to the atmosphere either at the ends of the tubing,

and at intermediatel points, no false alarms can occur 'through expansion of air 11n the tubing due to ordinary atmospheric'Stems- The prolonged 'open' pcrature changes. ends or' the tubing, or the vents'22 on' the detectors,l permitthe pressure Wlthm the ,tubing 'to be always "the same as that of the external air, ex'ceptzuhen a fire odeurs, s-mce atmospheric temperature changes are necessarily slow, 'as compared with temperature changes due tothe occurrence ofa tire. It, for anyrason, it be preferred vto close the ends'of the detector tubing, then the diaphragm contact deiiees will beprovided with restricted escape means Q2, 'as shown for example'. in Fig. 2, which restricted es.

. cape means permit inflowas Well'as outflow' of air, so that except, in the casev of abno-r" -mal expansion ef tlie air due to the occur-4 of the nearest detector or detectors, with re-A sulting closing of contacthetweexrthe diaphragm and Contact screw of that detector or detectors;` and the closing of such eon"' taet completes a shunt across the terminals ofl the transmitter magnet 6, 'denf' ergizing said magnet and so setting the transmitter in operation." .As the' wave of air, due to the abnormal rise in temperature, spreads in bot-h directions through Athe tubing 1, other. detectors will -be operated, so that' .in the eventO of the possible failure -of the first operated detector or cletectors to close circuit, other detectors, oper.- ated almost immediately thereafter, Will close circuit,so that unless all ofthe deteetors of thesystemare inoperative, or unless 'all' of the Wires leading from the'detectors to theannuncia-'tor are broken, or.

unless .the wire 64 leading from the battery to the detectors is broken, an, alarm will surely result. AAll ofthe 'detectors 'of the system are therefore available vfor the transmission of an alarm dueto excessive rise in temperature occurring in any portion of thel system, sineethe .n.'ave'o air spreads in bothl directionsfe'f the tubing,"and after operpoint ogorigin of the v;`ue,.will operatethe detectors of .other groups'to the very end Yating thefdetec'tors of .the group nearest'the.

of the system. That all ofthe annunciators are thus' -nally qoperated isv not: material, because, in most cases, the firemen vWillarrivebefore all .of the'groups oi" detectors .have been operated, and the middle annunciator'drep ofthosedropsjwhich have been moved to .display position, will. he, ordi.

narilyfa dropc'o'n'nected to a group of detectors ator .n'ear the point of' origin of the fire. 1

,1n-.uns application-*1 haie notiuus'tratea in full the; transmitting eircuitswhich I pres fer to use. 'In my companion application Sr. No. 712,764' I have illustrated transmitter circuits such that batteryeircuits are al Ways under. test, and such that even if the,

wir@ si smaad be broken before the-begin:

ning ofthe alarm, current for the opera-l tion of 'the system .ivil l bei received tlirougl'r i Asliillustrated particularly'in-Fig.; 6, the .tubing may be arranged as an endless' loop And l--l designate the v:several annuncior lengt-h of tubing. "lnthi'sgure, 1 desig-ig 'nates such endless loop' or length of tubing,

ator VWires leading from t-lie'several groups.

of detectors'2, to; the 'several annunciator` `magnets. 'It Will' be clear that the operation.

of vthis system' is the same as that shown'in Fig. 1'. From 'this fgnreand theiother' figiires'of the case it Will be clear thatthe lengtlrpf tubing provided @with restricted term is used l 1erei n`and in the following claims, denotes `Aa lengfh'oftubing provided with a restricted 'opening to the atmosphere.- at one or more points; butv this tubing may! be open atthegendsvvhen the ends extend an 'appreciable distance beyond the lasttesting device, or may be closed at the -ends and provided With'res'tricted escape-means at some' vother pointer points, cr may 'be endless and provided with restricted 'escape' means at one or more points.

VhatI claim is y v atmospheric pressure and provided with restricted escape'me'ansftov the atmosphere and adapted'tobe exposed to the heatof a fire,

and a plurality of fluid-pressure-actuated alarm-initiating dev ices connecte-dito said tubingv at various points along ,the length lof the same and intermediate the ends, thereof;

A temperature-alarm apparatusicomprising a length of tubing containing air'at atmospheric pressure and provided with restricted escape means to the atmosphere and L A temperature-alarm' apparatus-,cpm prising a length oftnbing containing air at lio adapted to beA exposed vto the heat'ot' a fire,

and a plurality of 4; iluid-pressure-actuated 'ralentir-initiating devices connected to said 'tubing v at various points along the length of :39

the saine and intermediate the ends thereof, and 'means adapted to be actuated by said alarm-initiating devices for indi-catingab# atmospheric pressure and provided with' restricted escape means to the atmosphere .and

adapted to be exposed to-'th'e heat yof a'fire,

and a plurality of ,'fluid-pressure-.actuated alarm initiating".devices connected'to said tubing at'various points 'along the ,lengthof the same and intermediate the endsthereof,

and alarm-transmitting means controlled'by ;V

' i a plurality of duid-pressureactuated alarmsaid signal initiating devices. A, temperature-alarm` apparatus comprising 'a length of tubing' containing air at atmosplieiic. pressure and provided'ivith re# stricted escape means to the atmosphere and adapted to be exposed to the heat oiu a tire,

yand a plurality of itluid-pressur'e-.actuated I. contact devices connectedto-said tubing at.

various points along the length of tlie same and intermediate the" ends thereof, and arranged to be actuated by expansion of air in said tubing, an electric circuit controlled b v said contact devices, and alarm-giving means actuated by said circuit.

' 6. A 4temperaturesalarin apparatus coniprising a length ,oftubing containing air at atmospheric pressure and adapted to been` posed to the hea-tof a fire, and al plurality' of ti'uid-pressure-actuated `alarin-initiating devices connected to said tubing at various points along the length of the saine and intermediate the ends thereof, and irestricted escape means connected to said tubing and arranged to permit tlov'vof air into and out of said tubing to compensate for normal temperature changes.

7. A temperature-alarm apparatus coinprising alengtli -oftubin'g containing air at atmospheric temperature -and adapted to be .exposed to the lieat of a tire, and a plurality 'of iuid-pressureactuated' alarm-initiating devices, connected to said tubing atv various points along the length of the same and intermediate the .ends thereof, and alarm-giving means controlled in common by said alarm-initiating devices, whereby' in the event of a tire the alarm-initiating devices are actuated successively, beginning with the device or devices nearestthe point at which heat iiist iniuences theiair Within said tube,

and whereby, in event of failure of the first Wave of air flowing' through said tube will actuate other alarm initiating devices.

' 8. A temperature-alarm Vapparatus come prising a length'of tubingy containing air at atmospheric pressure and provided with 'restricted escape means to the atmosphere and' adapted to-'be exposed'to the yheat ot' a lire, anda plurality of groups of fluid-pressureactuated alarm-initiating devices, connected Ito said' -tubing at variousl points along the length of the same and intermediate the ends thereof' each suchv Orou ,com risiriff a.

, i a e ,plurality alarm-'initiating devices, separat'epannunc'iating. meansl for eachsuch group and controlled thereby, and alarm` giving -means controlled in common by said alarm-initiatingdevices. v.

9. A #temperature-alarm apparatus coinl prisingv a. length ott-ubing-containing air at atmospheric pressure and provided with restricted escape means to the atmosphere andv adapted to be exposed to the liea-t of the fire,

initiating devices' connected to said tubing various points along the length' of the same and intermediate the ends thereof, a suction-operated testing device connected to said tubing beyond one of the extreme alarm-initiating devices, and suction producing means connected toI the tubing beyond the other of .the extreme alarm-initiating devices, and signaling means arranged to be operated by said suction operated device.

10. A temperature-alarm apparat-us comp'risiiig a length of tubing containing air at atn'iosplieric pressure and provided with restricted escape means to the atmosphere and adapted to be' exposed to the heat of the fire, a plurality vof fluid-pressure-actuated alariii-initiating devices connected to said 'tubing atl various' points alongrthe length of the saine andinterinediate the'ends thereof, a suction-operated testing device connected to said tubing beyond one of theextreinealarm-initiating devices, and suction. 'producingmea-ns connected to thel tubingbeyond the-other of tlie'extreme alarm-initiating'devices, signaling'ineans arranged to be operated 4by said suction operated device, said tubing being open beyond tlie point o'f connection of thesuction producing means thereto, and av valve arranged to -connect such main portionof tubing to such suction `producing means, or to the open portion ot' the tubing beyond the point of connection of the suction producing means, at Will.

11. A temperature-alarm apparatus comprising a length of tubing containing air at` atmospheric pressure and provided with restricted escape means to the atmosphere and adapted to be exposed to `the heat of the tire, a plurality of uid-pressureactueted vis at atmospheric pressure and provided with 'said tubing being open thereto,

tion producing means,

alarminitiating devices connected to said tubing at various points along the length of the same and intermediate the ends thereof, a suction-operated device connected to said tubing beyond one of the extreme alarm-initiating devices, and suction producing means connected to the tubing beyond the'other of the eXtreme alarni-i'nitiating devices, signaling means arrangedto be operated by said suction operated device, beyond the point of connection of the suction producing means and a valve arranged to connect .such main portion of the tubing to suchsuction of the tubing beyond the point of connection of the suction producing means, at will, said valve having Weighted operating means tending normally. to hold the valve in position to connect the main portion. of the tubing with the open portion thereof.

12.- A `temperature-alarm apparatus comprising a length of tubing containing air restricted-escape means to the atmosphere or to the open por-v and adapted to be exposed to the heat` of aiirc, and three or more luid-pressure-actuated alarm-initiating and distant. from one vices connected to said Atubing at various points `along the length tant from one another, saidA tubing provided at one or more points With restricted es cape means arranged to permit iiow of air into and out of said tubing to compensate for .normal temperature changes.

specification in `the presence of tivo subscrib ing Witnesses. A y

l 4JAMES G. IN-OLEN. wWitnesses:

H, M MARBLE, D; A. DAvins.

a ire, and three or more Huid-.pressure-actuated alarm-initiating de-f` of the same and disin testimony whereof l have signedv this Y devices connected to y said tubing at various points along the. 

